Co-regulation of the copper vacancy concentration and point defects leading to the enhanced thermoelectric performance of Cu 3 In 5 Te 9 -based chalcogenides.

Copper vacancy concentration ( V c ) in ternary Cu-In-Te chalcogenides is an important factor to engineer carrier concentration ( n H ) and thermoelectric performance. However, it is not sufficient to regulate the phonon scattering in the Cu 3 In 5 Te 9 -based chalcogenides. In this work we manipulate the V c value and point defects simultaneously through addition of Cu along with Ga substitution for In in Cu 3 In 5 Te 9 , and thereby increase the carrier concentration and reduce the lattice thermal conductivity. This strategy finally enables us to achieve ∼60% enhancement of the TE figure of merit ( ZT ) at V c = 0.078 compared with the pristine Cu 3 In 5 Te 9 . It is also used as guidance to achieve the high TE performance of the ternary chalcogenides.